The present invention relates generally to the leak testing and replacement of gloves that are utilized in gloveboxes, isolators, or containment units, and, more particularly, to the in-situ leak testing of gloves installed within these work enclosures.
A glovebox, isolator, or containment unit (herein collectively referred to as xe2x80x9cgloveboxxe2x80x9d) is a controlled environment work enclosure providing primary containment for the work area within the enclosure. Operations are performed through sealed gloved openings for the protection of the worker, the environment, and/or the product. The enclosure typically utilizes tight-closing doors or air locks, armholes with impervious gloves sealed to the box at the gloveport, and exhaust ventilation to keep the interior of the box at negative or positive pressure relative to the surroundings.
A particular glovebox hazard involves the occurrence of a visually undetectable leak within one or both of the gloves. This breach of the enclosure area can lead to contamination outside or inside the enclosure area. This can be extremely dangerous to the workers using the glovebox when the materials within the glovebox are hazardous to one""s health. This situation may also lead to contamination of an expensive product. At the present time, the commonly used method to determine whether the integrity of a glove has been compromised is when materials within the glovebox are detected outside the enclosure or when materials outside the glovebox are detected within.
In order to become more efficient at glovebox, isolator, or containment unit operations, a long felt need has existed to determine if the gloves utilized contain pinhole leaks without first experiencing a failure. The following published applications and patents were located that address this need: [1] Japanese patent application, 56140232 JP, xe2x80x9cDefect Checking Method for Installed Glove, Etc.xe2x80x9d discloses a method of determining defects within a glove by using a light source within the glove box and then inserting a photosensitive device into the installed gloves to detect any fight streaming through defects that may be present, [2] Japanese patent, JP 6-75092/A/, xe2x80x9cRubber Glove Wearing Devicexe2x80x9d, describes a device for checking gloves that entails securing them in an orifice of an enclosure that is then placed at negative pressure to provide the motive force for extending the glove within the enclosure. The pressure within the enclosure is then monitored to determine the presence or absence of glove failures, [3] U.S. Pat. No. 5,734,323, xe2x80x9cPuncture Detecting Barrier Materialsxe2x80x9d, uses a process of measuring the conductivity, resistivity, or capacitance between the conductive layers of multi-layer protective gloves to determine if the subject glove has been compromised.
The present invention, an in-situ leak testing plug, utilizes a completely different testing apparatus and methodology, and is based on a glovebox glove changeout plug originally designed at Los Alamos National Laboratory in the 1970""s. FIG. 1 is an exploded view of this glove replacement plug. Top plate 10, sealing mechanism 20, and base plate 30 each define a center penetration 40, 50, and 60, through which threaded bolt 70 passes. As handle 80 is turned to engage the threads on threaded bolt 70, the distance between top plate 10 and base plate 30 is reduced, providing pressure on sealing mechanism 20 to diametrically expand from beneath top plate 10 and base plate 30 against a gloveport opening, sandwiching the replacement and defective glove between sealing mechanism 20 and a gloveport. This particular feature of the prior art is beneficial to the present invention, as it allows for insertion of an in-situ leak testing plug without introducing shearing forces that might tear an otherwise perfectly good glove. Top plate 10, sealing mechanism 20, and base plate 30 include one or more penetrations 45, 55, and 65, that allows the air within the glove, that would normally be trapped during a solid plug insertion, to vent out.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
In accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention includes a test plug for in-situ testing a glove installed in a glovebox having a top plate with an interior surface that defines a circumferential groove, a base plate spaced apart from the top plate a variable distance, a diametrically expandable sealing mechanism fitting within the top plate circumferential groove and having a sealing exterior surface. The sealing mechanism engages the base plate to diametrically expand when the variable distance between the top plate and the bottom plate is reduced. An inlet valve is located on the top plate for introducing a pressurized gas into the glove, and a pressure gauge on the top plate to monitor the interior glove pressure.